1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device and a method for manufacturing the same that can remove a defect generated from polishing and etching of a glass substrate.
2. Background of the Related Art
Recently, research of flat panel displays such as liquid crystal displays (LCD), plasma display panels (PDP), electroluminescent displays (ELD), vacuum fluorescent displays (VFD), etc., is being performed, and these displays are being used in various apparatuses.
Among these displays, LCDs are most widely used in that they have good picture quality and low power consumption characteristics. They are being used as the display in portable televisions and notebook computers.
Portable televisions or notebook computers are obtaining their popularity because they are lightweight. A main component of technology development is to further decrease their weight. To this end, there are specific efforts to decrease the weight of the LCD itself.
Various ways for decreasing the weight of the LCD have been attempted. However, LCD structure and current technology limit the decrease of weight and size to the main elements of the LCD.
In the meantime, a glass substrate, which is one of the most basic elements of the LCD, still has a margin available for decreasing the weight of the LCD according to developments in processing technologies. Since the glass substrate occupies most of the total weight of the LCD, research for decreasing the weight of the class substrate is being performed for the purpose of decreasing the weight of the LCD.
In order to decrease the weight of the glass substrate, its thickness should be decreased incrementally. However, if the thickness decreases below a specific value, the glass substrate is broken during its processing or cracks are generated. Therefore, there is a limitation in decreasing the thickness of the glass substrate.
As a way for decreasing the thickness of the glass substrate, after an LCD panel is fabricated using a glass substrate having the specific thickness or more, a surface of the glass substrate is etched by dipping the glass substrate in an etching bath in which an etchant is contained.
This method, however, has disadvantages in that the glass substrate is disproportionally etched due to the incompleteness of the glass substrate itself, or foreign particles generated during the etching process stick to the etched surface of the glass substrate and thus the surface of the glass substrate becomes irregular.
A general LCD device and a method for manufacturing the same will be described with reference to following drawings.
FIG. 1 is a sectional view of the general LCD device.
As shown in FIG. 1, in the general LCD device, first glass substrate 3 and second glass substrate 4 are assembled together by a sealing pattern 6 to form some space therebetween. The general LCD device includes an LCD panel consisting of a liquid crystal 5 injected into the space between the first glass substrate 3 and second glass substrate 4 and charged by an electric field; polarizers 2-1 and 2-2 formed in upper and lower portions of the LCD panel; and a backlight 1 providing light from the back of the polarizer 2-1.
A method for manufacturing the LCD panel of the aforementioned LCD device will be described briefly.
A plurality of the LCD panels according to desired sizes are formed on a pair of large sized glass substrates having spaces corresponding to a plurality of the LCD devices. The pair of large sized glass substrates are assembled together to form some space therebetween, and then are cut according to the respective LCD panels. Subsequently, the liquid crystal is injected into the spaces between the glass substrates of the cut LCD panel.
Gate lines and data lines are formed on one of the glass substrates in each LCD panel to define pixel regions in a matrix arrangement. Also, the gate lines are formed to cross the data lines. A thin film transistor and a pixel electrode are arranged in each of the respective pixel regions. Then, a color filter layer and a common electrode are arranged on the other glass substrate in each LCD panel. Such glass substrates are aligned with each other, and are assembled with each other by a sealant to form space between the glass substrates. As aforementioned, the glass substrates are cut according to the respective LCD panels, and the liquid crystal is injected therebetween.
In this process, the assembled glass substrates are etched by etching equipment to reduce the weight of the LCD device before cutting the pair of glass substrates according to the respective LCD panels.
Prior to etching, a signal line, a thin film transistor, a pixel electrode, a color filter, and a common electrode (not shown) are formed on the first and second glass substrates having a thickness (t) of about 1.1 mm, and then the first and second glass substrates are assembled with each other as shown in FIG. 2A.
As shown in FIG. 2B, after the first and second glass substrates are assembled together, outer surfaces of the first and second glass substrates having a thickness (t′) of about 0.5 mm, for example, are etched by chemical etching or mechanical polishing processes.
However, in the etching process, grooves 11 or scratches occur in the glass substrates. For this reason, the outer surfaces of the glass substrates assembled with each other become irregular. This results in the occurrence of dot or spot defects on a screen during driving the LCD device.